This invention relates to a method for forming a skin-contacting topsheet of a disposable diaper with an elastic opening for reliable introduction of excretions.
Japanese Utility Model Application Disclosure Gazette No. 1974-120439 discloses a diaper-cover having a topsheet formed at its central zone with an opening extending longer in the longitudinal direction than in the transverse direction of the topsheet, wherein the opening is provided along its peripheral edge with a longitudinally stretchable elastic member so as to define a closed loop-shaped elastic line. Japanese Patent Application Disclosure Gazette No. 1986-41304 also discloses a disposable diaper having a topsheet formed at its central zone with an opening extending longer in the longitudinal direction than in the transverse direction of the topsheet, wherein the opening is provided along its laterally opposite side edges with elastic members, respectively.
With these diaper-cover and diaper both having the openings, excretions flow through said opening into pockets defined between said topsheet and a separately provided topsheet underlying the first-mentioned topsheet and is held therein, making it possible to avoid or at least alleviate apprehension that the wearer's skin might be smeared with excretions spreading over the skin-contacting uppermost topsheet, give the wearer unpleasant feeling and even cause the wearer to be attacked with a skin disease.
The above-identified Japanese Utility Model Application Disclosure Gazette No. 1974-120439 and Japanese Patent Application Disclosure Gazette No. 1986-41304 both disclose neither a method for forming the skin-contacting topsheet with the opening nor a method for attaching the elastic member around the opening. According to the former, it is supposed that the whole peripheral edge of the opening is provided with an elastic member in the endless fashion and then said elastic member is covered with the peripheral portion of the opening. However, no specific method is found in the specification. In view of the fact that the former relates to a reusable diaper-cover, the method probably employs the cutting and sewing techniques well known in the art. According to the latter, the central portion of the sheet is cut away to form the opening and both side edges of the opening are provided with the respective elastic members bonded to rear sides of the respective side edges with use of adhesive. Consequently, the diaper provided by the latter is not only unseemly but also poor in a desired strength along the peripheral edge of the opening because the elastic members are not covered at all although they are provided on the rear side of the sheet. Moreover, such an arrangement will not result in formation of neatly uniform gathers along the whole peripheral edge of the opening and therefore it can not be expected that the whole peripheral edge of the opening tightly bears against the wearer's skin.
It is a principal object of the invention to form a skin-contacting topsheet of a disposable diaper with an opening of which the whole peripheral edge presents the desired strength and contains therein elastic members covered with the topsheet.